Texans defensive end J.J. Watt walks across the field during warm ups.

Texans defensive end J.J. Watt walks across the field during warm ups.

Photo: Brett Coomer / Houston Chronicle

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Texans running back Arian Foster stands on the field before the game.

Texans running back Arian Foster stands on the field before the game.

Photo: Brett Coomer / Houston Chronicle

Image 63 of 63

Fitzpatrick has up-and-down first half against Broncos

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DENVER – More than eight minutes remained in the second quarter. But with the Texans leading 7-3, veteran starting quarterback Ryan Fitzpatrick had sharper numbers than Broncos all-world QB Peyton Manning.

An overthrow of Andre Johnson (80) was one of the mistakes made by Texans QB Ryan Fitzpatrick early in Saturday’s game at Denver. (Brett Coomer / Houston Chronicle)

An A.J. Bouye interception of Manning set up the Texans’ first score. Then Fitzpatrick channeled his preseason game No. 2-self, marching the Texans 57 yards on eight plays in 4 minutes, 36 seconds. By the time the Texans held a four-point advantage with 8:23 left in the first half Saturday at Sports Authority Field, a journeyman starter still trying to prove himself in Houston had outthrown the QB face of the NFL.

Fitzpatrick was 9-of-13 for 74 yards and an 83.5 rating, beginning with short-range passes to set up the offense, then opening his range as the game progressed.

Running back Jonathan Grimes, rookie tight end C.J. Fiedorowicz, and wide receivers DeAndre Hopkins and Keshawn Martin collected offerings, while veteran wideout Andre Johnson was targeted five times and hauled in three passes for 18 yards in his preseason debut.

But for all of Fitzpatrick’s early progress, the 10-year vet again showed why many have questioned his ability to consistently lead the Texans in 2014.

Manning eventually found his regular-season rhythm, throwing two touchdown bombs to wide receiver Emmanuel Sanders within 1:02 of action. By the end of the first half, the Super Bowl-winner (and D.J. Swearinger-taunter) was a sparkling 21-of-27 for 243 yards, two touchdowns and a 113.4 rating.

Fitzpatrick flamed out before the first half was complete. Unable to answer Manning’s first TD – a 67-yard loft to Sanders near the middle of the field – Fitzpatrick nearly threw an interception on his first pass and fired low on his second. A Texans punt followed, setting up Manning’s second torch.

The Texans’ 7-3 lead was suddenly a 17-7 Broncos advantage.

Fitzpatrick’s first-half numbers: 10-of-17, 80 yards, 70.7 rating.

The untouchable QB on the field had rediscovered his legendary aim.

Fitzpatrick was trailing again and only average.

Backup Case Keenum received yet another opportunity to prove himself in the second half.

For 18 plays, 74 yards and 9:37, the former University of Houston star guided the Texans on a mostly efficient drive, marking marked Keenum’s best run of the preseason. While two throws – including a third-down attempt near the Broncos’ end zone – were nearly intercepted, Keenum was often on target and displayed improved command of the Texans’ offense.

A 24-yard Randy Bullock field goal capped the drive, pulling the Texans within 17-10 with 5:23 left in the third quarter.

Keenum went 7-of-10 for 46 yards during the series, posting a 79.6 rating and reestablishing his hold as the Texans’ backup QB.

But the ex-Cougar’s second drive wasn’t as sharp. Keenum threw another near-interception to open the series, then badly threw high. A second-down attempt saw Keenum running backward and immersing himself in trouble, mirroring his worst 2013 trait. A hard sack followed, ending the drive.